Hydro-formed film with three-dimensional micro-apertures

Abstract

A method of processing a polymeric web includes providing a forming screen configured for supporting and moving with the web in a machine direction. The forming screen has a plurality of elliptical screen openings, each having a major axis perpendicular to the machine direction and a minor axis parallel to the machine direction. The method includes continuously depositing the web onto the forming screen and passing the web and forming screen through a water stream having a pressure level sufficient to cause the web to be forced into the screen openings, thereby forming protrusions extending from the planar surface of the web. Each protrusion has an apex, an opening at the apex, and an elliptical cross-section parallel to the planar surface of the web. The elliptical cross-section has a protrusion axis ratio that may be selected so as to produce a desired protrusion axis ratio.

What is claimed is: 
     
       1. A film comprising:
 a polymeric web having first and second opposing, substantially planar web surfaces; and 
 a plurality of three dimensional perforations through the polymeric web, each three dimensional perforation comprising a hollow protrusion extending from the first planar web surface, each protrusion having an apex, an opening at the apex having a circumference defined, at least in part, by a plurality of irregularly shaped petals, and an elliptical cross-section parallel to the planar surface of the web, the elliptical cross-section having a protrusion axis ratio in a range of 0.65 to 1.35, 
 wherein the plurality of three dimensional perforations were formed using a hydroforming process, and 
 wherein the localized protrusions are formed in the web in a two-dimensional pattern having a mesh count in a range of about 40 to about 75. 
 
     
     
       2. The film according to  claim 1 , wherein the protrusion axis ratio range is about 0.9 to 1.1. 
     
     
       3. The film according to  claim 2 , wherein the protrusion axis ratio is about 1.0. 
     
     
       4. The film according to  claim 1 , wherein the film has a compression sensor point of at least about 80. 
     
     
       5. A film according to  claim 1 , wherein the two-dimensional pattern is configured so that the localized protrusions are aligned in the traverse direction and staggered in the machine direction. 
     
     
       6. A method of forming a film, comprising a polymeric web having first and second opposing, substantially planar web surfaces, the method comprising:
 providing a forming screen configured for supporting and moving with the web in a machine direction, the forming screen having a screen wall with a plurality of elliptical screen openings formed therethrough, each screen opening having a major axis dimension perpendicular to the machine direction and a minor axis dimension parallel to the machine direction; 
 continuously depositing the web onto the forming screen so that the web is supported by the screen wall and so that the web and the forming screen wall move together in the machine direction; and 
 passing the web and forming screen wall through a water stream haying a pressure level sufficient to cause the web to be forced into the screen openings, thereby hydroforming localized protrusions extending from the first planar surface of the web, each protrusion having an apex, an opening at the apex having a circumference, defined at least in part, by irregularly shaped petals, and an elliptical cross-section parallel to the planar surface of the web, the elliptical cross-section having a protrusion axis ratio in a range of 0.65 to 1.35, 
 wherein the localized protrusions are formed in the web in a two-dimensional pattern having a maximum mesh count in a range of about 40 to about 75. 
 
     
     
       7. The method according to  claim 6 , wherein the protrusion axis ratio range is about 0.9 to 1.1. 
     
     
       8. The method according to  claim 7 , wherein the protrusion axis ratio is about 1.0. 
     
     
       9. The method according to  claim 6 , wherein the screen opening axis ratio is in a range of about 1.15 to about 2.50. 
     
     
       10. The method according to  claim 6 , wherein the step of providing further comprises selecting a screen opening axis ratio so as to produce the protrusion axis ratio as desired. 
     
     
       11. The method according to  claim 6 , wherein the film has a compression sensor point of at least about 80. 
     
     
       12. The method according to  claim 6 , wherein the two-dimensional pattern is configured so that the localized protrusions are aligned in the traverse direction and staggered in the machine direction.